[Xapian-devel] Something to think about

[Olly Betts]

On Sun, Oct 14, 2007 at 01:11:21PM +0100, James Aylett wrote:
> If the db is opened each time, the document ids aren't guaranteed to
> be consistent anyway, so does that case actually matter?

I'm not sure I follow.  For a single database or fixed collection of
databases, the docids of existing documents won't change between
searches, unless you mean that some documents may have been deleted.

Obviously that doesn't apply if you reindex from scratch, or if the
initial document has been deleted and you run xapian-compact without
--no-renumber, but in the common case of databases being updated, the
docids are stable with the interleaving scheme.

And for things like marking documents for relevance feedback, stability
of docids between searches is pretty much essential, which is why
we originally chose the interleaving scheme.

Cheers,
    Olly